The present invention relates generally to emission spectroscopy, and more particularly relates to a spectroscopic system which is capable of separating radiation emitted by semi-transparent materials from graybody radiation emitted by opaque materials.
In many instances it is desirable to measure infrared radiation emitted from a particular material while disregarding radiation emitted from background materials. Infrared emission spectra often convey the same information as absorption spectra with respect to chemical composition, state, and thickness of many materials. One important aspect of emission spectra is its strong dependence on temperature, which is substantially greater than that of absorption spectra. This dependence has its origin in the temperature dependence of thermal radiation in general. By being able to establish the temperature of a material such as fluid film from the shape of its infrared emission bands, much of the doubt which now exists with respect to total radiation pyrometry will be removed. However, it is often extremely difficult to separate radiation emitted by a material such as a fluid from radiation emitted by metal parts, dust, metal fragments, etc.
One area in which it is desirable to detect emitted infrared radiation is in the contact region of a lubricant fluid with a simulated bearing contact. From simulated bearing contact, it is easier to detect emitted radiation than absorbed radiation as it is rather difficult to pass radiation through the bearing surface and the lubricant to a detector. With a simulated bearing contact, it would be desirable to determine the fluid and metal surface temperatures and also changes of fluid composition and state under various operating conditions. The infrared spectra of semi-transparent fluid films generally consist of discontinuous radiation of discrete bands, which are characteristic of the composition and state of the material, whereas infrared emission spectra of metallic surfaces are continuous, graybody radiation, and generally depend only upon temperature. It would be desirable to separate these composites of the spectra, as this would enable the accumulation of data on the fluid, and would allow deductions regarding the mechanisms of elastohydrodynamic (EHD) processes, particularly those leading up to failure.
The measurement of emitted infrared radiation is also desirable in other areas. The existence of geochemical fossils (hydrocarbons and other organic matter) in rock removed in drilling cores is frequently used as an indicator of the availability of oil and gas deposits further down in the earth's crust. The analysis of the kerogen in the form originally present in the rock is of particular interest. Extraction, pyrolosis, and other means of removing the organic matter from the rock for analysis often change the nature of these organic materials sufficiently so that important clues are lost. It would be desirable to be able to make an in situ, nondestructive analysis of the kerogen.